$ \left(\dfrac{5}{3}\right)^{-4}$
Solution: $= \left(\dfrac{3}{5}\right)^{4}$ $= \left(\dfrac{3}{5}\right)\cdot\left(\dfrac{3}{5}\right)\cdot \left(\dfrac{3}{5}\right)\cdot \left(\dfrac{3}{5}\right)$ $= \dfrac{9}{25}\cdot\left(\dfrac{3}{5}\right)\cdot \left(\dfrac{3}{5}\right)$ $= \dfrac{27}{125}\cdot\left(\dfrac{3}{5}\right)$ $= \dfrac{81}{625}$